It is well known that artwork is viewed as an important developmental tool for children. For example, marking materials, such as paints and markers, are given to children for drawing, painting, and coloring purposes in order to stimulate their creativity and imagination. Of course, a significant drawback with conventional marking materials is that they tend to become very messy in use. Indeed, parents often limit the use of marking materials by children because of the possibility that household objects, such as carpets and furniture, as well as skin and clothing, would be stained by the marking materials.
The inherent messiness of known marking materials is exacerbated by the fact that the undesirable stains are usually extremely difficult to remove. In this regard, the propensity to leave enduring stains on both skin and clothing is one of the most objectionable properties intrinsic to most coloring instruments used by young children. Accordingly, much effort has been expended over many years by producers of these instruments to reduce or eliminate staining. This is attested to by the rather numerous offerings of so-called "washable" markers, which on close examination, are found to remove very poorly from fabrics that are typically used in children's clothing.
For example, European Patent Publication No. 0017889 describes a prior art approach for providing a writing system based on a chemical color reaction. However, the formulations described in European Patent Publication No. 0017889 are unsatisfactory because they are toxic and the dyes undesirably precipitate out of solution quickly. In addition, the onset of premature coloration is an especially significant problem when using the materials disclosed under this approach. Further, the formulations disclosed in European Patent Publication No. 0017889 cause the development of very heavy stains that are extremely difficult to remove and are essentially non-washable.
Accordingly, it will be appreciated that there exists a need for a marking system that inhibits the formation of inadvertent stains on household objects or other unintended surfaces during use. Particularly, there exists a need for a marking system that is not only substantially non-staining to household objects and other unintended surfaces, but which is also non-toxic, simple to make and use, chemically stable, and capable of rapidly generating various colors. It will also be appreciated that there exists a need for a marking system in which any unwanted stains can be readily removed by washing. It is an object of the present invention to provide such a marking system satisfying these needs. These and other objects and advantages of the present invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.